Pearls on sleep disorders in ALS

1. In ALS starting NIV at 70 % predicted FVC preserves life longer than if begun at 50 %. (life extension of 2.7 vs. 1.8 yrs)

2. In ALS CSA and OSA occur early, but OSA drops out, and thoracoabdominal paradox occurs in 30 % and is difficult to test with PSG.

3.  Testing should use multiple modalities including nocturnal O2 sats,  supine FVC, NIF not necessarily PSG. pCO2 more than 45 may be enough.

4.  Bulbar disease especially with FTD is a major risk for nonuse of NIV

5.  Siallorrhea can be treated with benadryl or elavil which also helps sleep and does not mandate non use of NIV

6.  Sleep labs are not set up for ALS patients for many reasons -- lack of facilities for lifts, caregivers, et al.

7.  Classic bilevel devices for central apneas don't account for short shallow breathing in ALS.  Newer pressure control devices that guarantee a longer inspiratory time with a targeted tidal volume are much better.  Need a tidal volume of 8cc/kg IBW.  This used to be achieved by classic ventilator with a mask.

8.  Inappropriate devices such as servo ventilation devices (designed for Cheynes-Stoke breathing) decreased minute ventilation and is not good for ALS.  Autotitrating bilevel devices are designed for use in OSA and are not good in ALS.

9.  Ease of breathing comes from frictional work, with expansion of chest wall, and elastic work, with expansion of lung itself. Lower breaths per minute maximizes elastic work, higher bpm maximizes frictional work, with combined benefit somewhere in the middle with 20 or so bpm.

10.F/ Vt (respiratory rate /tidal volume) is a useful surrogate marker for wob, or work of breathing.  If its less than 33, work of breathing should be OK.    Note that Vt (wob) is proportional to (I-E)/R*T, where (I-E), or the difference between IPAP and EPAP is pressure support, and R  is resistance (which may be increased by kyphoscoliosis eg.) and T is inspiratory time, which turns out to very important in these patients.SLOW deep breathing may be easiest factor to manipulate in these patients.

11. Settings that are important: slow rise time of ventilation in bulbar disease (fast rise time in diaphragmatic disease), inspiratory time of .8 to 1.4 seconds, trigger and cycle adjustments to improved comfort, and tubing sleeve for increased humidity.